You seem to be discussing in good faith here, and I think it’s worth continuing so we can both get a better idea of what the other is saying. I think differing non-verbal intuitions drive a lot of these debates, and so to avoid talking past one another it’s best to try to zoom in on intuitions and verbalize them as much as possible. To that end (keeping in mind that I’m still very confused about consciousness in general): I think a large part of what makes me a machine functionalist is an intuition that neurons...aren’t that special. Like, you view the China Brain argument as a reductio because it seems so absurd. And I guess I actually kind of agree with that, it does seem absurd that a bunch of people talking to one another via walkie-talkie could generate consciousness. But it seems no more absurd to me than consciousness being generated by a bunch of cells sending action potentials to one another. Why should we have expected either of those processes to generate consciousness? In both cases you just have non-mental, syntactical operations taking place. If you hadn’t heard of neurons, wouldn’t they also seem like a reductio to you?
What it comes down to is that consciousness seems mysterious to me. And (on an intuitive level) it kind of feels like I need to throw something “special” at consciousness to explain it. What kind of special something? Well, you could say that the brain has the special something, by virtue of the fact that it’s made of neurons. But that doesn’t seem like the right kind of specialness to me, somehow. Yes, neurons are special in that they have a “unique” physico-chemical causal structure, by why single that out? To me that seems as arbitrary as singling out only specific types of atoms as being able to instantiate consciousness (which some people seem to do, and which I don’t think you’re doing, correct?). It just seems too contingent, too earth-specific an explanation. What if you came across aliens that acted conscious but didn’t have any neurons or a close equivalent? I think you’d have to concede that they were conscious, wouldn’t you? Of course, such aliens may not exist, so I can’t really make an argument based on that. But still—really, the answer to the mystery of consciousness is going to come down to the fact that particular kinds of cells evolved in earth animals? Not special enough! (or so say my intuitions, anyway)
So I’m led in a different direction. When I look at the brain and try to see what could be generating consciousness, what pops out to me is that the brain does computations. It has a particular pattern, a particular high-level causal structure that seems to lie at the heart of its ability to perform the amazing mental feats it does. The computations it performs are implemented on neurons, of course, but that doesn’t seem central to me—if they were implemented on some other substrate, the amazing feats would still get done (Shakespeare would still get written, Fermat’s Last Theorem would still get proved). What does seem central, then? Well, the way the neurons are wired up. My understanding (correct me if I’m wrong) is that in a neural network such as the brain, any given neuron fires iff all the inhibitory and excitatory inputs feeding into the neuron exceed some threshold. So roughly speaking, any given brain can be characterized by which neurons are connected to which other neurons, and what the weights of those connections are, yes? In that case (forgetting consciousness for a moment), what really matters in terms of creating a brain that can perform impressive mental feats is setting up those connections in the right way. But that just amounts to defining a specific high-level causal structure—and yes, that will require you to define a set of counterfactual dependencies (if neurons A and B had fired, then neuron C wouldn’t have fired, etc). I was kind of surprised that you were surprised that we brought up counterfactual dependence earlier in the discussion. For one I think it’s a standard-ish way of defining causality in philosophy (it’s at least the first section in the wikipedia article, anyway, and it’s the definition that makes the most sense to me). But even beyond that, it seems intuitively obvious to me that your brain’s counterfactual dependencies are what make your brain, your brain. If you had a different set of dependencies, you would have to have different neuronal wirings and therefore a different brain.
Anyway, this whole business of computation and higher-level causal structure and counterfactual dependencies: that does seem to have the right kind of specialness to me to generate consciousness. It’s hard for me to break the intuition down further than that, beyond saying that it’s the if-then pattern that seems like the really important thing here. I just can’t see what else it could be. And this view does have some nice features—if you wind up meeting apparently-conscious aliens, you don’t have to look to see if they have neurons. You can just look to see if they have the right if-then pattern in their mind.
To answer your question about simulations not being the thing that they’re simulating: I think the view of consciousness as a particular causal pattern kind of dissolves that question. If you think the only thing that matters in terms of creating consciousness is that there be a particular if-then causal structure (as I do), then in what sense are you “simulating” the causal structure when you implement it on a computer? It’s still the same structure, still has the same dependencies. That seems just as real to me as what the brain does—you could just as easily say that neurons are “simulating” consciousness. Essentially machine functionalists think that causal structure is all there is in terms of consciousness, and under that view the line between something being a “simulation” versus being “real” kind of disappears.
Does that help you understand where I’m coming from? I’d be interested to hear where in that line of arguments/intuitions I lost you.
I think a large part of what makes me a machine functionalist is an intuition that neurons...aren’t that special. Like, you view the China Brain argument as a reductio because it seems so absurd. And I guess I actually kind of agree with that, it does seem absurd that a bunch of people talking to one another via walkie-talkie could generate consciousness. But it seems no more absurd to me than consciousness being generated by a bunch of cells sending action potentials to one another.
Aren’t neurons special? At the very least, they’re mysterious. We’re far from understanding them as physico-chemical systems. I’ve had the same reaction and incredulity as you to the idea that interacting neurons can ‘generate consciousness’. The thing is, we don’t understand individual neurons. Yes, neurons compute. The brain computes. But so does every physical system we encounter. So why should computation be the defining feature of consciousness? It’s not obvious to me. In the end, consciousness is still a mystery and machine functionalism requires a leap of faith that I’m not prepared to take without convincing evidence.
But even beyond that, it seems intuitively obvious to me that your brain’s counterfactual dependencies are what make your brain, your brain.
Yes, counterfactual dependencies appear necessary for simulating a brain (and other systems) but the causal structure of the simulated objects is not necessarily the same as the causal structure of the underlying physical system running the simulation, which is my objection to Turing machines and Von Neumann architectures.
you could just as easily say that neurons are “simulating” consciousness. Essentially machine functionalists think that causal structure is all there is in terms of consciousness, and under that view the line between something being a “simulation” versus being “real” kind of disappears.
it’s an interesting thought, and I generally agree with this. The question seems to come down to defining causal structure. The problem is that the causal structure of the computer system running a simulation of an object does not appear anything like that of the object. A Turing machine running a human brain simulation appears to have a very different causal structure compared with the human brain.
You seem to be discussing in good faith here, and I think it’s worth continuing so we can both get a better idea of what the other is saying. I think differing non-verbal intuitions drive a lot of these debates, and so to avoid talking past one another it’s best to try to zoom in on intuitions and verbalize them as much as possible. To that end (keeping in mind that I’m still very confused about consciousness in general): I think a large part of what makes me a machine functionalist is an intuition that neurons...aren’t that special. Like, you view the China Brain argument as a reductio because it seems so absurd. And I guess I actually kind of agree with that, it does seem absurd that a bunch of people talking to one another via walkie-talkie could generate consciousness. But it seems no more absurd to me than consciousness being generated by a bunch of cells sending action potentials to one another. Why should we have expected either of those processes to generate consciousness? In both cases you just have non-mental, syntactical operations taking place. If you hadn’t heard of neurons, wouldn’t they also seem like a reductio to you?
What it comes down to is that consciousness seems mysterious to me. And (on an intuitive level) it kind of feels like I need to throw something “special” at consciousness to explain it. What kind of special something? Well, you could say that the brain has the special something, by virtue of the fact that it’s made of neurons. But that doesn’t seem like the right kind of specialness to me, somehow. Yes, neurons are special in that they have a “unique” physico-chemical causal structure, by why single that out? To me that seems as arbitrary as singling out only specific types of atoms as being able to instantiate consciousness (which some people seem to do, and which I don’t think you’re doing, correct?). It just seems too contingent, too earth-specific an explanation. What if you came across aliens that acted conscious but didn’t have any neurons or a close equivalent? I think you’d have to concede that they were conscious, wouldn’t you? Of course, such aliens may not exist, so I can’t really make an argument based on that. But still—really, the answer to the mystery of consciousness is going to come down to the fact that particular kinds of cells evolved in earth animals? Not special enough! (or so say my intuitions, anyway)
So I’m led in a different direction. When I look at the brain and try to see what could be generating consciousness, what pops out to me is that the brain does computations. It has a particular pattern, a particular high-level causal structure that seems to lie at the heart of its ability to perform the amazing mental feats it does. The computations it performs are implemented on neurons, of course, but that doesn’t seem central to me—if they were implemented on some other substrate, the amazing feats would still get done (Shakespeare would still get written, Fermat’s Last Theorem would still get proved). What does seem central, then? Well, the way the neurons are wired up. My understanding (correct me if I’m wrong) is that in a neural network such as the brain, any given neuron fires iff all the inhibitory and excitatory inputs feeding into the neuron exceed some threshold. So roughly speaking, any given brain can be characterized by which neurons are connected to which other neurons, and what the weights of those connections are, yes? In that case (forgetting consciousness for a moment), what really matters in terms of creating a brain that can perform impressive mental feats is setting up those connections in the right way. But that just amounts to defining a specific high-level causal structure—and yes, that will require you to define a set of counterfactual dependencies (if neurons A and B had fired, then neuron C wouldn’t have fired, etc). I was kind of surprised that you were surprised that we brought up counterfactual dependence earlier in the discussion. For one I think it’s a standard-ish way of defining causality in philosophy (it’s at least the first section in the wikipedia article, anyway, and it’s the definition that makes the most sense to me). But even beyond that, it seems intuitively obvious to me that your brain’s counterfactual dependencies are what make your brain, your brain. If you had a different set of dependencies, you would have to have different neuronal wirings and therefore a different brain.
Anyway, this whole business of computation and higher-level causal structure and counterfactual dependencies: that does seem to have the right kind of specialness to me to generate consciousness. It’s hard for me to break the intuition down further than that, beyond saying that it’s the if-then pattern that seems like the really important thing here. I just can’t see what else it could be. And this view does have some nice features—if you wind up meeting apparently-conscious aliens, you don’t have to look to see if they have neurons. You can just look to see if they have the right if-then pattern in their mind.
To answer your question about simulations not being the thing that they’re simulating: I think the view of consciousness as a particular causal pattern kind of dissolves that question. If you think the only thing that matters in terms of creating consciousness is that there be a particular if-then causal structure (as I do), then in what sense are you “simulating” the causal structure when you implement it on a computer? It’s still the same structure, still has the same dependencies. That seems just as real to me as what the brain does—you could just as easily say that neurons are “simulating” consciousness. Essentially machine functionalists think that causal structure is all there is in terms of consciousness, and under that view the line between something being a “simulation” versus being “real” kind of disappears.
Does that help you understand where I’m coming from? I’d be interested to hear where in that line of arguments/intuitions I lost you.
Thank you for the thoughtful reply.
Aren’t neurons special? At the very least, they’re mysterious. We’re far from understanding them as physico-chemical systems. I’ve had the same reaction and incredulity as you to the idea that interacting neurons can ‘generate consciousness’. The thing is, we don’t understand individual neurons. Yes, neurons compute. The brain computes. But so does every physical system we encounter. So why should computation be the defining feature of consciousness? It’s not obvious to me. In the end, consciousness is still a mystery and machine functionalism requires a leap of faith that I’m not prepared to take without convincing evidence.
Yes, counterfactual dependencies appear necessary for simulating a brain (and other systems) but the causal structure of the simulated objects is not necessarily the same as the causal structure of the underlying physical system running the simulation, which is my objection to Turing machines and Von Neumann architectures.
it’s an interesting thought, and I generally agree with this. The question seems to come down to defining causal structure. The problem is that the causal structure of the computer system running a simulation of an object does not appear anything like that of the object. A Turing machine running a human brain simulation appears to have a very different causal structure compared with the human brain.